Art of printing



Dec. l0, 1935. v, DlETz 2,023,669

ART OF PRINTING Filed Jan. 6, 1953 E @1' CELLuLo/D BHJE GE'HT/N "HV R y l Pumas/UM on DIW LIGHT .SENSITIVE FILM PHO T0 NEG/7T] VE III,

PRIN TING F RH ME wnsuzo .swoLLEIv FILM .mmmm v PRIN TIA/G PHPEF? JOHN DDE JANE SMITH y HTnMa 3mm;

CUT OPHQUE .JTENCILI Patented Dee.- 1o, 1935 UNITED STATES 2,023,669 Aar oF PRINTING Valentin Dietz, Cologne, Germany, assignor to Erwin B. Elliott and Maurice C. Boyd, both of Miami, Fla.

Application January 6, 1933,.Serial No. 650,880

` In Germany October 11, 1932 12 claims'. (ol. iol-149)l Heretof-cre printing with ink applied to a wet, swollen, gelatin stratum or layer on a Celluloid film or other suitable base or foundation andincorporating the image or design to bereproduced depressed in the surface of such layer has been practised with a measure. of success.

In performing such process the gelatin layer is made light-senstitive by immersing it in an ammonium bichromate or potassium bichromate solution and subsequently drying it,.such dry,

' gelatin-coated lm being thenexposed to light through the photographic negative or other matter` to be printed.

The gelatin stratum by suchlight exposure throughout its various portions becomes more or less tanned or set or made incapable of being swollen by water or made Water-insoluble, depending upon the intensity of the light which has reached it through the negative or other supersoluble or unsusceptible to distension by Water, depending upon the .degree of translucency of the corresponding areas of the negative.

Such light-treated, gelatin-coated lm is then Washed in Water to dissolve out the bichromate from those sections of the gelatin which the light has not reached and from those portions which the light has only partially set or tanned.

Thereupomthe surface of the gelatin layer is wipedover or coated with an ink-repellent consisting of water or a Water-glycerine mixture, with or without the addition of one or more alkals, to prevent the adherence of the ink, when applied to such surface, in varying degreedepending upon the extent or measure of complete or partial hardening of the gelatin. l Y

Then the surface of such Wet stratum is coated with ink which adheres thereto in conformity with the differing degrees of tanning or hardening ofthe layer by the light to which it was exposed,

Vno ink cleaving to the wholly unlight-treated,

swollen portions of the layer, and the ink adhering to the remaining sections of the layer proportionally to their degree of tanning or hardening,-

This-having been accomplished, the sheet of paper or other medium to be printed is pressed on such inked surface of the gelatin stratum and then removed, the ink by such action being transferred to the paper as in the usual printing operation. Y

Then the inking and sheet impression are repeated for each'printing action, the film being frequently moistened or Wet with water or the glycerine-water mixture to maintain the ink repellent action of those parts thereof to which the ink should not adhere by compensating for the depletion of such repellent medium incident to the printing operation.

In the commercial performance of such process, l5 it is customary to wet or coat such gelatin layer with water or the glycerine-.Water mixture before each inking and printing operation and to insert suitable separation sheets between the moist,

printed sheets to prevent blurring or smearing.

It is possible, however, to print a number of "sheets, say 50 to 100 or more, before again applying such water to the gelatin to compensate for that withdrawn therefrom by the printing operation, but, under such circumstances, the quality of the prints becomes progressively inferior and it is for that reason that it is preferable' to wet the gelatin surface before each inking and printing action.

In this old wet process, owing'to the fact that 30 the water orglycerine and water mixture must be expelled or removed by the inking-roller from the depressed-image surface of the film to permit the ink to cling thereto, and, in view of the fact that theother portions of the films surface are more or less swollen and raised, a considerable pressure must be exerted by the inking-roller on the gelatin layer, with the natural consequence that a comparatively thick ink must Abe used to assure proper application thereof to the surface. 40

This necessity for a relatively-heavy, strong printing-press capable of applying the required pressure has precluded the use of such process in oces and the like where such a press would not be suitable for several reasons. 45

Accordingly, one of the aims of my invention is to provide a process and printing means which can be successfully used with a small, light, relaprinting-press exerting a suiciently lesser pressure so that the machine can be made at small cost and can'be satisfactorily employed in oiiices and the like, as mimeographs are now used, or the printing may be done by hand without the use of a machine or printing-press.

Another objection to such known wet process, aside from the requirement for frequently applying the ink-repellent water or glycerine-water mixture, resides in' the fact that the print produced is more or less moist or wet, with a natural tendency to smear or blur. My new process overcomes such objectionable characteristic of the old method.

Again, in the familiar old process, the contact of the ink on the rollers with the Water or the glycerin'e-water mixture progressively injures the quality of the ink and from time to time the contaminated ink has to be removed and replaced with fresh ink, which fault -is avoided in the performance of my novel process.

Because the glycerine-water mixture or water is applied to a water-swollen gelatin stratum, the latter, especially due to the high pressure used on it, is capable of making only a limited number of 'satisfactory prints, but in my new procedure, the layer is toughened, and this, coupled with the lighter pressure used, results in a materially larger number of available prints.

In the specified old, wet process, owing to the dampness of the print, the quality of the work is somewhat limited, but, in my newnon-moistening process, no such moisture being present in the print, a substantially higher grade of print is possible. .f

Further, in such wet method, when the printed sheet is stripped or removed from the gelatin stratum, it has a tendency to roughen the surface of such layer slightly, due to the stickiness of the gelatin, and, accordingly, this factor also tends to limit the useful life of the gelatin member and to lower the quality of the printed work. 'I'his fault is also overcome in the new process.

Some of the deficiencies of the old method of `printing reside in the continuous necessity for moistening the printing surface, the complexity of the process, the frequent occurrence of error, and the inability to print the nest outlines and half-tints with fidelity and accuracy.

In general, one of the prime objects and purposes of the present invention is the provision of a process which eliminates or surmounts the difficulties and weaknesses of the old methods and which permits the production of a considerably larger number of prints of an improved quality.

A further important aim of the invention is to supply a novel printing procedure which places the whole work on a simpler and more reliable basis than heretofore, in that it can be performed or carried out by relatively unskilled laymen, whereas the old methods have required considerable technical knowledge on the part of the operators, which curtailed the practice of the art to a comparatively small number of printing plants.

In the drawing:-

Figure 1 illustrates the soaking of the suitably supported gelatin layer or iilm in a potassium or ammonium bichromate solution;

Figure 2 presents the gelatin lm after it has been dried and become light sensitive;

Figure 3 shows the exposure of such lightsensitive lm to light through a photo or analogous negative;

Figure 4 portrays the'exposed fllm'after it has been washed and become swollen;

Figure 5 shows the same film after it has been dried;

Figure 6 indicates the soaking of the dried film in a bath to swell it and to render it ink repellent in conformity with the light developed image;

Figure 7 illustrates the swollen lm with its printing surface dried;

Figure 8 shows the inking of the surface of the film with an ink containing an ink repellent;

Figure 9 presents the printing operation;

Figure 10 shows a dry gelatin layer written or printed on with a medium to which a water solution of ammonium bichromate or potassium bichromate or their equivalent has been added;

Figures 11 and 12 illustrate another way of practising the procedure; and

Figure 13 shows the use of an opaque stencil in which the matter to be printed is cut.

According to the present, preferred method of practising my new and improved, non-moistening, printing process, the layer or stratum of gelatin, albumin, agar-agar, or other equivalent colloidal or gelatinous substance capable of swelling in water, mounted on a suitable backing or support, such as celluloid, water-proof paper, glass, etc., which may be transparent or merely more or less translucent, as may be preferred, (a white celluloid film being the best choice because it will readily disclose an undesired ink smear thereon when taken up for use) is immersed in a 5% solution of ammonium bichromate or potassium bichrcmate fcrabout one or two minutes (see Figure 1), whereupon it is taken ,from the bath and dried, the gelatin stratum becoming light-sensitive when dry (see Figure 2).

When removed from such bath, the gelatincoated film is laid between papers and pressed to expel the surplus solution to assist the drying, and then set aside to dry, preferably in a darkroom, because, as indicated above, when it becomes dry it acquires its light-sensitivity.

Then such completely dry film is mounted in an ordinary photographic printing-frame back of the photographic negative or other matter to be reproduced and exposed to the light in the manner usually employed in making photograph prints (see Figure 3) This asembling of the members in the frame -through the negative to daylight for about three or four minutes, or to full sunlight for about one minute, the length of time of course depending upon the nature of the material to be reproduced and the intensity of the light, it is removed from the frame and washed as by placing it in a waterbath (see Figure 4) Such exposure to the light hardens or renders the gelatin layer water-insoluble or incapable of swelling in water in its various parts in direct relation to the strength of the light which reaches them through the negative or other superposed element, and, as a-result, the water of the bath in which the film is immersed dissolves out all of the bichromate which has not been employed in so tanning the gelatin, such washing or soaking being continued until all or practically all of the free bichromate has been removed, which can be easily determined by the changed color of the film or of the wash water, whereupon the lm is taken from the bath and dried (see Figure 5).

Next, such dry iilm is introduced into an ink or color-repellent bath consisting of a mixture of water, glycerine, and ox-gall in the approximate proportion by weight of 24% water, 75% pure glycerine,' and 1% ox-gall concentrated to a strength of about solids at which concentrationv it is in the form of a sticky paste (see` Figure 6).

As a substitute for ox-gall the bile of other animals may be employed, or synthetic bile may be used.

Also, instead of using glycerine and water in the mixture, another polyhydric alcohol, glycol, may be substituted, in which case the mixture will f be in about the ratio by weight or glycol 99% and oX-gall v1%. f

To eitherof these twomixtures an alkaline substance,l such as sodium bicarbonate may or may not be added, but, if employed, it may comprise something like 2% of the mixture.

The soaking of the dry image-bearing gelatin-l coatedVv iilm in suchk bath causes those parts of- ,the gelatin stratum which have not been tanned or only partially tannedby light to swell and to absorb the ink-repellent mixture throughout the entire thickness of the gelatin layer in proportion to the degree of tanning or absence of tanning. which, of course, is in direct relation to the lightintensity previously imposed.

After the gelatin-coated im has been in such bath for approximately 15 minutes, the time period depending -upon the temperature of the bath, it is taken out and the surplus solution removed from its surface (see Figure 7), but such surface drying does not eliminate or reduce itsswelled properties, and such treated gelatin layer, if it has been mounted on a celluloid film or its equivalent, is pliable and it can be used repeatedly for securing the greatest number of prints therefrom without requiring any wetting or moistening, as was frequently necessary by the oldprocess.

An excess period of soaking of the coated lm in the swelling and repellent bath seems to have no substantial detrimental effect on it.

The reason for drying the film after the bi- -chromate has been washed out, rather than introducing the wet, swollen gelatin layer into the repellent bath, is to assure that, by resoaking and reswelling the dried stratum, the repellent will penetrate through the e-ntire thickness of the gelatin and the ox-gall will be carried-throughout the thickness of the layer simultaneously with' its swelling.

adhere at all to the corresponding sections of the layer, but, for the other portions of the layer, it cleaves in more or less amount or thickness in conformity with their ink-repellent prop- Then the sheet of paper or other material to be printed is pressdon such inked surface by hand or by machinef'hd removed, the ink by such action being"trf `l erred from the surface of the gelatin layer to the paper, as in the usual printing procedura Such inking of the unmoistened, swollen gelatin layer and the printing thereby may be continued over a long period without injuring the gelatin and without'substantial decrease in the quality of the prints produced.

In designating the'surfaceof the swollen gelatin stratum as unmoistened, it is to be understood that it is not wet in the sense that it does not have a layer or lm of any wetting or moistening medium spread or present on it, but the swollen body of the gelatinl may contain more or less water, the small water content of the ox-gall in the applied ink, referred to hereinafter, 5 being of no significance.

The term ink-repellent as applied to the bile or ox-gall, has been employed with the meaning that the specified material performs the function of augmenting or reenforcing the capacity of the swollen gelatin stratum to reject the applied ink and to preserve and prolong indenitely the property of the distensible gelatin to repel the ink, thus permitting the stratum to be used unwetted during any printing operation and over the entire service period of the stratum.

The expression gelatinous is used to designate any colloidal medium capable of swelling in water'.

l It has been found, however, that due to the 20 continued application of the inking-roller over the surface of the gelatin stratum and by reason of the repeated pressing of the print paper on the gelatin surface, the material which makes the gelatin ink repellent' is gradually or progressively removed or abstracted from the gel- Even though this increasing or developing surface depletion or exhaustion of the ink-repellent may be more or less overcome or replaced by the ink-repellent in the body of the gelatin layer worklng'its way to the surface, it has been discovered that it is desirable to specifically or continuously replace such extracted. or withdrawn material so that it will be present in the.. gelatin nlm at all times substantially in its full or A'required amount. A

This result'can be readily and easily accomplished by properly charging the ink with a suitable amount of an ink-repellent, especially 40 the ox-gall, and a convenient and appropriate mixture would be as follows: Lamp-black about 22%, medium-consistencyv linseed-oil-varnish approximately 66%, and ox-gall about `1,3% (see Figure 8). f 1

The amount of lnk-repellent to be used cannot always be stated with accuracy, because the quantity-to be incorporated in the ink depends in substantial measure the kind and quality of the rcolor employed and the grade and consistency of the linseed-oil-varnish. i

'I'he correct proportion of ink-repellent to. be mixed or combined with the ink can be comparatively easily determined by simple tests, bearing in mind that, if too little is used, the gelatin layer will be gradually starved of its repellent, which effect will be indicated by the character of the prints; whereas if too much is put in the ink, the ink will not properly adhere to those sections of the gelatin layer to which it should cleave.

Thus for each application of ink, a suitable supply of the ink-repellent is also. made to the geatin layer, which either prevents the withdrawal of such repellent from the gelatin or 65 replaces that which may be abstracted, but in either case, the result is the same in that the' gelatin at all times is in proper condition for printing and does not become exhausted or deprived of any of its essential constituents.

The ink-repellent mixture' acts not only to make the condition of the gelatin such that it `will not receive the ink, but it also makes the swollen gelatin rmer and tougher than has heretofore beenpossible and without substantial 75 modification of its swelling properties, and, accordingly, the gelatin layer can be used for producing a large number of prints of the highest quality.

Seemingly both the glycerine and glycol and the ox-gall tend to give the swollen portions of the gelatin substantially improved wearing properties.

Although I have indicated the use of ox-gall as a peste, it is to be understood that it can be employed in powder form if preferred.

The specified oX-gall when incorporated in the ink has the further advantage that it causes the ink. to dry and harden rapidlyso that danger of smearing the prints is overcome.

The preferred procedure set forth in detail above is the one ordinarily employed where a considerable number of prints is required (see Figure 9), but in those cases where a comparatively small number of prints suffices the inkrepellent may be incorporated in the gelatin stratum alone or in the ink alone.

Since the gelatin-coated film is printed from without wetting it, and because such gelatin layer is firmer and tougher than when merely swelled with water or water and glycerine, the printing can be accomplished with a thinner ink and a lesser pressure than has heretofore been necessary, the quality of the work is better, the number of possible prints is greatly increased, and the gelatin film lasts much longer.

By reason of the fact that the image to be printed is dened by the varying degrees of inkrepellency in the different parts of the gelatin film, which extend throughout its entire thickness, the layer wearsmuch longer without obliterating or substantially-injuring the image than has been possible in the past.

Attention is also directed to the fact that since an ink can be used with my new style of gelatin lm, such as is ordinarily employed in printing from type, photographic illustrations and type printing can be carried on simultaneously with the lsame ink, and the fact that the ink may contain some of the specified ink-repellent is not a detriment so far as the type printed portion is concerned, because the ink dries and hardens quickly, a desirable factor in the printing industry. l

It has been stated above that the employment of the ink-repellent oX-gall makes the swollen gelatin stratum tougher and harder, and it may also be remarked that the particular ink-repellent mentioned reduces the stickiness or adhesiveness of the gelatin Surface, thus lessenng the tendency to withdraw or abstract the repellent from the gelatin during the printing operation.

Stated somewhat differently, the use of the repellent oX-gall tends to maintain the surface of the gelatin comparatively smooth, whereas by the old wet process there was a distinct tendency to cause it to become somewhat rough.

It has been discovered further thatfinstead of charging or impregnating the Whole of the gelatin stratum with a bichromate or other substance or substances having the same or equivalent effect on the gelatin when dried and exposed to light, only those portions of the gelatin layerwhich it is desired to tan or make hard or incapable of swelling in water may have the light-sensitizing medium applied thereto or impressed thereon.

Stated otherwise, if desired, the dry gelatincoat of a Celluloid film may be written or printed on by hand or by a typewriter or otherwise with a medium to which-a water solution of ammonium bichromate or potassium bichromate or their equivalent has been added in appropriate amount (see Figure 10).

When such bichromate-coated portions of the 5 gelatin layer dry they become light-sensitive, and the light acting on them directly and/or through the transparent or translucent backing tans or sets those portions only of the layer so that they cannot swell under the action of water. 10

In such instance, the bichromate-coated parts of the gelatin'rst swell up and then shrink, all of the bichromate apparently being consumed in hardening and setting the gelatin.

Inasmuch as there is no excess of, or unused, 15 bichromate in such dry film, it is not necessary to wash it, and such dry, tanned lm is then immersed in the ink-repellent bath and the procedure above specified followed.

If a few prints only are required from such lm, 20 instead of placing it in the ink-repellent bath it may be swollen with glycerine and water or glycol, without the additional repellent, the operator depending solely upon the repellent in the ink for accomplishing the desired result from such 25 unmoistened-surface, swollen stratum.

Since such printing or writing is done directly on the gelatin film, the printing therefrom must be reversed, as, for instance, by offset printing.

It may be observed that in all instances the 30 printing is done from an unmoistened surface of a swollen gelatin layer and that the ink-repellent is used either in such stratum or in the ink or in both the stratum and ink.

Instead of writing directly on the surface of 35 the gelatin, the writing or printing may be first done on a sheet of paper and then the face of such paper applied to the surface of the dry gelatin before the writing orprinting medium has-had a chance to dry. 40

Another method is to provide an unmoistened, swollen gelatin stratum on the celluloid or other backing, then to write or print the desired matter on a sheet of paper with an ink or other medium containing the water solution of bi- 45 chromate (see Figure 1l), then to press the printed face of the sheet'on the surface of the swollen gelatin, allowing it to remain there long enough for the bichromate to affect the gelatin, then to remove the sheet of paper, allow the gela- 50 tin layer to dry to make it light-sensitive, then to expose it to light, and then to proceed as above (see Figure 12).

In the practice of the immediately preceding procedure, the ink-repellent may be incorporated 55 in the swollen gelatin layer-before the sheet of paper is applied thereto or after it has been subjected to the action of light by soaking it in the bath of ink-repellent, or the repellent may be used solely in the ink when a few prints only 60 are required.

' ableo-r desirable to use such sodium glycocholate rather than the cheaper ox-gall either in the gelatin layer, or in the ink, or in both. 75

aoaaoeo OX-gall and sodium glycocholate are alkaline and so far as I know the use of an alkaline inkrepellent in the ink is wholly novel.

Instead of following 'exactly any of the above- Specified courses, it is possible to cut the matter to be printed on a typewriter inv an opaque stencil without the use of any typewriter ribbon (see Figure 13), so that the typewritten matter is transparent or translucentthe remainder of the Stencil maintaining its opaqueness-and then to use such negative over the light-sensitive gelatin layer during the light exposure.

In such case the right or reverse side of the negative may be used against the gelatin, de-

pending upon whether direct or oiset printing is to be employed.

Hereinbefore I have referred to the use of sodium bicarbonate in the gelatin layer, this being used for the purpose of affording the layer a favorable printing-surface state under thel existing atmospheric conditions.

In some instances, however, it is preferable to employ another alkaline substance as a substitute for the bicarbonate.

Accordingly, and perhaps more especially when the process is practiced under somewhat dry conditions of the atmosphere, it is better to use in the neighborhood of one-quarter of one per cent by weight of para-phenylenedamine in the glycerine-water-bile bath and to employ about one-quarter of one per cent of the same ingredient in the ink, or the specified chemical or its equivalent may be incorporated solely in the gelatin layer or in the ink alone.

Of course, the amount of such chemical to be employed may be readily ascertained, if necessary, by easily conducted, tests to meet the specific atmospheric conditions encountered.

Those acquainted with this art will readily understand that this invention, as defined by the appended claims, is not necessarily limited to the precise and exact details set forth and that various changes may be resorted to without departure from the invention and without the loss or sacrifice of any of its material benefits and advantages.

I claim:

1. In the art of printing, tanning the parts of a suitably-supported gelatinous layer in agreement with the image to be printed by such layer to make them incapable of swelling in'varying degree by the swelling medium employed, swelling the distensible parts of such layer and at the same time making them ink-repellent by an agent other than the swelling medium and incorporating at least one bile salt, inking the unmoistened printing surface of'said layer by an ink containing said agent ,as an ingredient and printing with such inked surface.

2. The process set forth in claim 1 in which.

ing the distensible .parts of such layer and at the same time making them ink-repellent by a bath in the approximate proportion by weight of 75% pure glycerine, 24% water, and 1% bile salts (75% solids), inking the unmoistened printing surface of said layer by an ink containing bile salts, and printing with such inked surface. 5

4. In the art of printing, tanning the parts of a suitably-supported gelatinous layer in agreement with the image to be printed by such layer to make them incapable of swelling in varying degree by the swelling medium employed, swelling the distensible parts of such la er and at the s ame time making them ink-repe lent in a bath comprising water and glycerine and containing as two additional agents, a bile salt and an amine, inking the unmoistened printing surface of said layer by an ink containing one of said agents and printing with such inked surface.

5. In the art of printing, tanning the parts of a suitably-supported gelatinous layer in agreement with the image to be printed by such layer to make them incapable of swelling in varying degree by the swelling medium employed, swelling the distensible parts of such layer and at the same time making them ink-repellent by an agent other than the swelling medium, charging at least the surface of said layer with an amine before printing therewith, inking the unmoistened printing surface of said layer by an ink containing said agent as an ingredient, and printing with such inked surface.

6. The process set forth in claim 5, in which said amine is para-phenylenediamine.

7. ,In the art of printing, tanning the parts of a suitably-supported gelatinous layer in agreement with the image to be printed by such layer to make them incapable of swelling in varying degree by the swelling medium employed, swelling thedistensible parts of such'layer and at the same time making them ink-repellent by an agent other than the swelling medium, inking the un- 40 moistened printing surface of said layer by an ink containing said agent as an ingredient and an amine, and printing with such inked surface.

8. 'Ihe process set forth vin claim 7 in which said amine is para-phenylenediamine. 9. In the art ofprinting, tanning the parts of a suitably-supported gelatinous layer in agreement with the image to be printed by such layer to make them incapable of swelling in varying degree by the swelling medium employed, treating said layer with a medium capable of swelling said layer and making said layer ink-repellent, said medium containing an amine agent other than the swelling medium, inking the unmoistened printing surface of said layer by an ink containing said agent and printing with such inked surface.

l0. The process presented in claim 9 in which the agent other than the swelling medium is para-phenylenediamine.

11. The process presented in claim 9 in which the agent other than the swelling medium contains at least one bile salt. Y

12. The process presented in claim 9 in which the agent other than the swelling medium contains ox-gall.

VALENTIN DIETZ. 

